U.S. patent number 5,491,938 [Application Number 08/272,032] was granted by the patent office on 1996-02-20 for high damping structure.
This patent grant is currently assigned to Kajima Corporation. Invention is credited to Tomohiko Hatada, Masatoshi Ishida, Takuji Kobori, Narito Kurata, Takayuki Mizuno, Naoki Niwa, Motoichi Takahashi.
United States Patent |
5,491,938 |
Niwa , et al. |
February 20, 1996 |
High damping structure
Abstract
A high damping device combined with the frame of a building to
protect the building from seismic shock. For seismic vibration up
to a predetermined level corresponding to the permissible strength
of the high damping device, a damping coefficient c of the high
damping device is set so as to be c.sub.3 =c=c.sub.1 with respect
to a damping coefficient c.sub.3 for giving the maximum value of a
damping factor h.sub.3 corresponding to a tertiary mode of
vibration of the structure and a damping coefficient c.sub.1 for
giving the maximum value of a damping factor h.sub.1 corresponding
to a primary mode of vibration. The maximum load on the high
damping device is predetermined and means are provided to prevent
the high damping device from being damaged in the event that the
predetermined maximum load is exceeded. The inventive combination
permits the stiffness factor of the building to be reduced from a
factor of 1.0 down to a factor as low as 0.3, with a proportionate
reduction in steel frame mass.
Inventors: |
Niwa; Naoki (Tokyo,
JP), Kobori; Takuji (Tokyo, JP), Takahashi;
Motoichi (Tokyo, JP), Kurata; Narito (Tokyo,
JP), Mizuno; Takayuki (Tokyo, JP), Ishida;
Masatoshi (Tokyo, JP), Hatada; Tomohiko (Tokyo,
JP) |
Assignee: |
Kajima Corporation (Tokyo,
JP)
|
Family
ID: |
27330383 |
Appl.
No.: |
08/272,032 |
Filed: |
July 8, 1994 |
PCT
Filed: |
October 18, 1991 |
PCT No.: |
PCT/JP91/01426 |
371
Date: |
June 17, 1992 |
102(e)
Date: |
June 17, 1992 |
PCT
Pub. No.: |
WO92/83333 |
PCT
Pub. Date: |
May 14, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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861842 |
Jun 17, 1992 |
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Foreign Application Priority Data
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Oct 19, 1990 [JP] |
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2-280712 |
Aug 30, 1991 [JP] |
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3-219959 |
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Current U.S.
Class: |
52/167.1;
52/167.3 |
Current CPC
Class: |
E04H
9/0237 (20200501); E04H 9/02 (20130101); E04H
9/028 (20130101) |
Current International
Class: |
E04H
9/02 (20060101); E04H 009/02 () |
Field of
Search: |
;52/167R,167CB,167DF,1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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52-13865 |
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Apr 1977 |
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JP |
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54-19710 |
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Jul 1979 |
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JP |
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56-23515 |
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Jun 1981 |
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JP |
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63-130940 |
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Jun 1988 |
|
JP |
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1-236333 |
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Oct 1989 |
|
JP |
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1-263332 |
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Oct 1989 |
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JP |
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1-263333 |
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Oct 1989 |
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JP |
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2-112536 |
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Apr 1990 |
|
JP |
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2-209568 |
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Aug 1990 |
|
JP |
|
2-209571 |
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Aug 1990 |
|
JP |
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2-236326 |
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Sep 1990 |
|
JP |
|
2-248542 |
|
Oct 1990 |
|
JP |
|
2-248581 |
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Oct 1990 |
|
JP |
|
3-235856 |
|
Oct 1991 |
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JP |
|
1318679 |
|
Jun 1987 |
|
SU |
|
Primary Examiner: Lindsey; Rodney M.
Attorney, Agent or Firm: Tilberry; James H.
Parent Case Text
This is a continuation of application Ser. No. 07/861,842, filed
Jun. 17, 1992, now abandoned.
Claims
We claim:
1. In combination, a multi-storied structure having column and beam
frame members; earthquake-resisting braces secured to and
reinforcing said frame members; non-variable, self-contained
passive hydraulic damping devices secured between said frame
members, or between one of said frame members and one of said
earthquake-resisting braces, or between said earthquake-resisting
braces on the individual stories of said multi-storied structure,
said passive hydraulic damping devices being energized solely by
seismic vibrations impacting on said frame members to independently
passively damp said seismic vibrations up to a predetermined level;
and fail safe means to prevent vibration overload on said
non-variable, self-contained hydraulic damping devices, said
non-variable, self-contained hydraulic damping devices having
predetermined non-variable damping coefficients preselected and
preset to provide damping factors within predetermined ranges.
2. The combination of claim 1, wherein said steel frame members
provide a structure having a stiffness factor within the range of
thirty to one hundred percent.
3. The combination of claim 1, wherein said damping factor is
within the range of ten to forty percent.
4. The combination of claim 1, wherein one or more of said passive
hydraulic damping devices are secured to one or more of said
stories of said multi-storied structure and the said non-variable
coefficients of damping of said non-variable passive hydraulic
devices are selectively preset and fixed for each of said stories
to coordinate the overall damping effect of said passive hydraulic
damping devices on seismic vibrations.
5. The combination of claim 4, wherein a plurality of said passive
hydraulic damping devices are secured to each of said stories of
said multi-storied structure.
6. The combination of claim 1, wherein said multi-storied structure
has high, intermediate, and low modes of natural vibration, and
said non-variable coefficients of damping of said non-variable
passive hydraulic damping devices are selectively preset and fixed
to maximize damping of said intermediate mode of vibration.
7. In combination, a multi-storied structure having column-and-beam
frame members; earthquake-resisting braces secured to and
reinforcing said frame members; and passive hydraulic damping
devices secured between said frame members or between one of said
frame members and one of said earthquake-resisting braces or
between said earthquake-resisting braces; said structure having
natural modes of vibration V.sub.1, V.sub.2 and V.sub.3 wherein a
damping coefficient c.sub.1 provides a maximum damping factor
h.sub.1, a damping coefficient c.sub.2 provides a maximum damping
factor h.sub.2, and a damping coefficient c.sub.3 provides a
maximum damping factor h.sub.3, in which the relationship of said
coefficients is c.sub.1 .ltoreq.c.sub.2 .ltoreq.c.sub.3 ; means to
provide said hydraulic damping devices with a fixed preset damping
coefficient c.sub.2 set at a predetermined level; means to preset
said hydraulic damping devices to prevent overloading by seismic
vibrations exceeding a preset predetermined level; and means to
maintain said damping coefficient c.sub.2 at said fixed preset
predetermined level.
8. The combination of claim 7, wherein said column-and-beam type
frame has a stiffness factor within the range of thirty to one
hundred percent.
9. The combination of claim 7, wherein the said damping factor
h.sub.2 is within the range of ten to forty percent.
10. The combination of claim 7, wherein said damping device
comprises a hydraulic cylinder having first and second pressure
responsive hydraulic chambers; means to permit hydraulic fluid to
flow from said first hydraulic chamber to said second hydraulic
chamber responsive to a first level of seismic force; means to
permit hydraulic fluid to flow from said second hydraulic chamber
to said first hydraulic chamber responsive to a second level of
seismic force; and said means to prevent said damping device from
becoming overloaded by vibrations including hydraulic relief valves
between said first and second hydraulic chambers.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of invention comprises devices for damping vibrations of
structures caused by seismic shock or the like.
2. Description of Related Art
A variety of active and passive seismic response control systems
are known, including variable stiffness devices, to provide for the
safety of structures. For instance, a variable stiffness
earthquake-resisting mechanism may be integrated in a
column-and-beam type frame structure in the form of an adjustable
brace in which the rigidity of the variable stiffness mechanism, or
the means of connection between the frame and the variable
stiffness mechanism, functions to analyze seismic vibrational
forces and to provide damping to offset these forces.
Prior art active seismic response control systems attempt to deal
with seismic vibrations by actively shifting the natural frequency
of the structure against the predominant period of a seismic
vibration. However, seismic motion is an irregular vibration which
does not have a clear predominant period, and in some instances,
the predominant period is plural. Furthermore, in the case of prior
art active seismic response control systems, various sensors as
well as a controlling computer are used. To safeguard against the
possibility of unforeseen events, a variety of safety maintenance
mechanisms are necessary, the control of which becomes complicated.
These safety mechanisms are not only costly, but require valuable
start-up time to become effective. During this start-up period, the
structure is either unprotected or not fully protected.
For instance, Kobori et al. U.S. Pat. No. 4,890,430 discloses an
active damper which is computer controlled to vary the natural
resonance of an entire building by actively varying the rigidity of
selected structural members. Kobori. et al. U.S. Pat. No. 5,022,201
is an active seismic damper comprising a mass damper mounted on the
top of a building. The damper is actively vibrated by an actuator
connecting the mass to the building. Ishii et al. U.S. Pat. No.
5,025,599 discloses a combination active and passive damping device
wherein a mass damper is rendered actively vibratable by a
hydraulic actuator. In the event of a power failure, the device is
converted to a passive damper wherein the mass is passively
vibratable by coiled springs between the mass and the building
which are excited solely by the energy of seismic vibration.
SUMMARY OF THE INVENTION
As used in this specification, the following definitions shall
apply:
1. Active damper shall mean a seismic vibration damping device
which, in order to function, requires an actuator energized by
means other than the energy of seismic vibration.
2. Passive damper shall mean a seismic damping device which
functions without an actuator and is energized solely by the energy
of seismic vibration.
3. Actuator shall mean a mechanical, electro-mechanical,
electrical, and/or electronic means for energizing an active
damper.
4. Control force shall mean the force applied by a seismic
vibration damping device to a structure to damp seismic vibrations
in the structure.
5. Fail safe means shall mean a device to automatically deactivate
a seismic vibration damper to protect the damper from damage due to
overload or malfunction.
6. Column and beam shall mean state of the art construction
materials used to form the vertical and horizontal frame portions
of a structure.
The basic concept of the invention is to use a rigid frame
structure with a stiffness factor of approximately one-half of the
stiffness and strength factor of a frame required in a normal
design. To compensate for the reduced rigidity of the frame
structure, the damping devices, in combination with
earthquake-resisting elements, such as braces, are secured to the
column-and-beam frame of the structure. Maximum damping capacity is
obtained for the structure, and the response of the structure is
minimized by preliminarily setting the damping coefficient of the
inventive high damping device at a proper value. Although a
structure having one-half of the frame stiffness of a prior art
structure is an example of a structure suitable for protection by
the inventive high damping device, the invention provides effective
protection for column-and-beam frames having a stiffness and
strength factor substantially within a range of 0.3 through 1.0 of
the stiffness of a prior art structure designed and equipped with
prior art earthquake-resisting devices. In the case where the
structure stiffness factor exceeds 1.0, seismic response reduction
becomes progressively less effective. On the other hand, where the
strength of the structure is less than 0.3, effective damping
becomes substantially impossible because of the shearing forces to
which the column-and-beam frame is subjected.
According to the present invention, earthquake-resisting braces are
provided within a predetermined column-and-beam type frame of a
structure. Either the column-and-beam frame and the braces are
interconnected with the inventive high damping devices, or only the
braces are interconnected by the inventive high damping devices,
which are capable of giving a damping coefficient c within a
predetermined range, including a damping coefficient for minimizing
the response of the structure to an earthquake.
With reference to the damping coefficient c of the high damping
device, a damping factor of each vibration mode of the structure is
obtained by the following formula (1):
wherein
.lambda.i:an i-th complex natural value
hi:an i-th damping factor, and
Re(.lambda.i):a real number part of the i-th complex natural
value.
The damping coefficient c of the high damping device is taken as
being set in the neighborhood of such damping coefficients c.sub.1,
c.sub.2 and c.sub.3 which give the maximum values of damping
factors h.sub.1, h.sub.2 and h.sub.3 corresponding to the primary
through tertiary vibration modes, respectively.
With reference to the damping capacity of the structure, a most
advantageous condition can be obtained by setting the coefficient c
within the range:
The damping coefficient c of the high damping device is
preliminarily set in the neighborhood of the damping coefficients
c.sub.1, c.sub.2 or c.sub.3 (e.g., 25 cm/sec) which provide the
maximum values of the damping factors h.sub.1, h.sub.2 and h.sub.3
corresponding to the primary through tertiary vibration modes as
described above, and the damping coefficient of the high damping
device is preset for the seismic motion at a predetermined
vibration level.
Seismic response control can also be accomplished by defining the
damping coefficient c as c.sub.a =F.sub.a /V.sub.L' wherein F.sub.a
is the permissible strength of the high damping device and V.sub.L
is a response velocity of the high damping device due to an
earthquake at a predetermined vibration level. The damping
coefficient c of the high damping device may also be expressed as
c.sub.x =F.sub.a /V.sub.x wherein F.sub.a is the permissible
strength of the high damping device and V.sub.x is a response
velocity of the high damping device due to an earthquake) for an
earthquake at the preceding predetermined vibrational level.
Assuming that the permissible strength F.sub.a of a single high
damping device is 100 tons, maximum damping is provided for the
structure while keeping the damping coefficient c at a
predetermined constant value of 25 tons per cm/sec responsive to
seismic vibration up to a level of 25 cm/sec, for an earthquake
having the maximum speed standardized to 25 cm/sec. The load is
kept at approximately 100 tons of the permissible strength by
gradually decreasing the preset damping coefficient from 25 cm/sec.
Within these parameters, damping can be provided for the structure
within the capacity of the device while at the same time protecting
the device from damage should the seismic vibrations exceed the
capacity of the device. It is desirable that the damping
coefficient c.sub.a within a predetermined vibrational level be
within the range of c.sub.3 through c.sub.1. When the damping
coefficient c.sub.a falls below this range, the damping
effectiveness decreases. Also, when the damping coefficient c.sub.a
exceeds this range, it becomes difficult to design a high damping
device having the capacity to damp such high energy vibration
loads.
OBJECTS OF THE INVENTION
It is among the objects of this invention to provide a passive
seismic response control mechanism which does not need as part of
the control system a computer program or the like; to permit a
structure to have a high damping capacity by properly connecting an
earthquake vibration resisting element, such as a brace, to a high
damping device, which are then interconnected within a
column-and-beam type frame structure; to reduce the vibrations of a
structure due to external disturbances such as earthquake, wind, or
the like; and to provide safe living space within the structure
during a seismic disturbance.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects and advantages of the invention
will be apparent from the following description of preferred
embodiments of the invention with reference to the accompanying
drawings, in which:
FIG. 1 is a schematic front elevational view of a structure
equipped with the inventive high damping devices;
FIG. 2 is a schematic front elevational view of a prior art
structure;
FIG. 3 is a schematic diagram of a vibration model of one-story of
a structure protected with the present invention;
FIG. 4 is a graph showing the relationship between the primary
through tertiary damping factors of a column-and-beam type frame
structure provided by primary through tertiary damping
coefficients;
FIG. 5 is a graph comparing responses to vibration of a prior art
structure and a structure protected with the inventive high damping
device;
FIG. 6 is a graph showing the relation between a seismic load and
the effect of the inventive high damping device;
FIG. 7 is a graph showing the relation between a seismic load and
the velocity of the inventive high damping device;
FIG. 8 is a basic schematic sectional view of the inventive high
damping device;
FIG. 9 is a cross-sectional view taken along line 9--9 of FIG.
8;
FIG. 10 is a schematic sectional view of another preferred
embodiment of the inventive high damping device;
FIG. 11 is a sectional view of yet another embodiment of the
inventive high damping device;
FIG. 12 is a sectional view of a pressure regulating valve used in
a preferred embodiment of the invention;
FIG. 13 is a sectional view of a relief valve used in a preferred
embodiment of the invention;
FIG. 14 is a sectional view of a by-pass line and an accumulator
device used in a preferred embodiment of the invention;
FIG. 15 is a schematic elevational fragmentary view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device secured to a system of
inverted V-braces;
FIG. 16 is a schematic fragmentary elevational view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device and U-shaped connecting brace
members;
FIG. 17 is a schematic fragmentary elevational view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device connected to a seismic
shock-resisting wall type brace and with the inventive high damping
device oriented in a horizontal mode on the top edge of the seismic
shock-resisting wall type brace;
FIG. 18 is a schematic fragmentary elevational view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device secured between a beam and
the foundation of the structure;
FIG. 19 is a schematic fragmentary elevational view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device in a horizontal mode secured
to a system of cross braces;
FIG. 20 is a schematic fragmentary elevational view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device secured to a system of cross
braces, similar to FIG. 19, but with the inventive high damping
device in a vertical mode;
FIG. 21 is a schematic fragmentary elevational view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device secured to a seismic
shock-resisting wall brace, similar to FIG. 17, but with the
inventive high damping device secured to a vertical side edge of
the seismic shock-resisting wall brace; and
FIG. 22 is a schematic fragmentary elevational view of an
embodiment of a post-and-beam type frame of a structure equipped
with an inventive high damping device, similar to FIG. 19, but with
the cross braces extended so as to secure a plurality of stories of
the structure with a single inventive high damping device.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
Referring first to FIG. 1, therein is shown a structure 1 employing
the inventive high damping device 10, having a column-and-beam type
frame which requires approximately only one-half of the columns 2
required of a conventional prior art structure, such as shown in
FIG. 2, having the same number of stories. Inverted V-type braces
4, functioning as earthquake-resisting elements, and high damping
devices 10 are locally installed at each floor level 3 to absorb
vibrational energy impacting the structure.
FIG. 3 schematically shows a single story model of the inventive
high damping device, in which c is the damping coefficient of the
device, K.sub.F is the stiffness of the column-and-beam frame, and
K.sub.V is the stiffness of the brace. With this model, the natural
value of a multi-story building can be obtained, and a damping
factor for each mode of the structure can be calculated by formula
(1), set forth above.
The graph of FIG. 4 shows the relation between the damping factor
h(%) of the frame's natural period and the damping coefficient c
(tons/cm/sec) of the inventive high damping device 10 for each
floor level of the structure with respect to primary through
tertiary coefficient modes and their corresponding damping factors.
If the damping coefficient c of the inventive high damping device
10 is set within the range a where each damping factor h.sub.1,
h.sub.2 or h.sub.3 falls within the range of 10 through 40%, a
sufficient response reduction effect to seismic vibration can be
obtained. Within this range a, the difference between the peak of
the tertiary damping factor h.sub.3 and the peak of the primary
damping factor h.sub.1 is significant, since it is advantageous to
obtain both a damping coefficient c.sub.3 which obtains the maximum
value of the damping factor h.sub.3 for the tertiary mode and a
damping coefficient c.sub.1 which obtains the maximum value of the
damping factor h.sub.1 for the primary mode, and to set the damping
coefficient c of the high damping device as c.sub.3
.ltoreq.c.ltoreq.c.sub.1.
If the damping coefficient c is less than c.sub.3, the deformation
of the frame rapidly increases. On the other hand, if the damping
coefficient c is more than c.sub.1, there is not much difference in
the vibration control effect, although the strength required for
the high damping device increases.
The graph of FIG. 5 illustrates the response reduction effect
observed on the basis of a seismic response spectrum. By
approximately halving the column-and-beam frame natural period
(T.sub.1) of a prior art structure, the natural period (T.sub.2) is
extended and the spectrum itself is lowered. At the same time,
since the damping effect increases by approximately 2% up to 10
through 40%, the response spectrum is further lowered and the
natural period is slightly shortened, as shown at T.sub.3. At this
time, the increase of the structural deformation, which normally
becomes a problem, can be controlled because the damping effect
increases.
With reference to the foregoing discussion of FIGS. 4 and 5, the
permissible strength of the high damping device should be taken
into consideration as well. Thus, since the load applied on the
inventive high damping device is roughly proportional to the scale
and velocity of the seismic vibrations when the damping coefficient
c is constant, when the damping coefficient c is decreased
responsive to an earthquake exceeding a predetermined level (e.g.,
25 cm/sec), the applied load will decrease to a level commensurate
with the designed strength of the inventive high damping
device.
FIGS. 6 and 7 are graphs showing effects of load on an inventive
high damping device. FIG. 6 shows the relationship between load and
displacement against a sine wave expressed as F=c.sub.V, wherein F
is a load applied on the inventive device, c is the damping
coefficient (tons/cm/sec) of the device, and V is the velocity
(cm/sec) of the device in response to an earthquake. Displacement
of the inventive device in response to a level 25 cm/sec earthquake
is indicated by the .delta..sub.25 arrow. Displacement of the
inventive device in response to a level 50 kine earthquake is
indicated by the .delta..sub.50 arrow. FIG. 7 shows the
relationship between load and velocity, and both figures indicate
an upper load limit of 100 tons. It is found that the damping
coefficient c of the inventive device decreases from a velocity of
V.sub.25 or a displacement of .delta..sub.25 in response to an
earthquake at a level of 25 cm/sec.
By way of example, assume a twenty-four story building, having a
rigid steel frame structure 98.1 m in height, 3.90 m in typical
floor height, and 1269 m.sup.2 in typical floor area, and assume
that the maximum velocity amplitude of the input seismic motion is
at a level of 50 cm/sec. Also assume that four inventive high
damping devices are required on every floor of the building in
order to have the required strength in the event of seismic loads
in the order of 200 tons. The damping coefficient c is set at 25
tons/cm/sec in order to limit the maximum load to under 100 tons
applied to each inventive high damping device, and the damping
coefficient c is decreased against earthquakes exceeding the 25
cm/sec level so as to avoid harmful increase of the load on each of
the inventive devices per se. Thus, in the inventive high damping
device the relationship between a load F and a velocity V produced
on the high damping device approaches linearity.
As an embodiment of the inventive high damping device 10, FIG. 8
shows its basic structure, wherein a piston 12, with piston rods
12a and 12b, is incorporated within a cylinder 11. Pressure
regulating valves 17a and 17b provide two-way flow paths through
the piston 12 to enable oil to flow freely between hydraulic
chambers 14a and 14b, depending on which hydraulic chamber is under
the greater positive pressure.
In order to protect the inventive device against overload (e.g., in
excess of the predetermined level), relief valves 27a and 27b are
provided in piston 12. When a pressure in excess of the designed
load is applied, either relief valve 27a or 27b opens to release
the pressure. In installations in which overload cannot occur, the
relief valves 27a and 27b may be eliminated.
FIG. 9 shows the arrangement of pressure regulating valves 17a and
17b and relief valves 27a and 27b, which are uniformly
circumferentially arrayed to form passageways through piston
12.
FIG. 10 diagrammatically shows an embodiment of the damping device
10 in which the piston rod 12a projects from the cylinder 11 only
in one direction, and fastening rings 15 and 16 are provided for
connecting the inventive high damping device to portions of a
frame, such as shown in FIGS. 15 through 22. The high damping
device of FIG. 10 includes an oil accumulator 18 in combination
with check valves 20a and 20b so that the damper will have an
adequate supply of oil at all times.
The embodiment of FIG. 11 shows in section pressure regulating
valves 17a and 17b which are provided within the piston 12 for the
purpose of preventing oil from leaking to the exterior of the
damper. The pressure regulating valves 17a and 17b are provided
with conical poppet valves to provide damping independent of
temperature. See also FIG. 12. For durability and reliability,
multi-stage metal seals 29a are used to seal the piston 12 for
sliding contact with cylinder 11. Two-stage metal seals 29b are
also used as fixed seals. In addition, seals 29c, made of a
fluorocarbon resin, are provided in two stages for the rod portion,
and the seal 29c on the external side is replaceable as a
cartridge. With this combination of sliding and fixed seals, a high
damping coefficient becomes possible by minimizing the potential
for high pressure oil leaks in the system. A three-directional
rotatable clevis may be used for connecting the fitting ring 15 to
a frame member.
Referring to FIG. 13, therein is shown, in an open-pressure
setting, spring 28 in relief valve 27. When the seismic vibration
of an earthquake exceeds a predetermined level of energy, resulting
in pressure at an inflow portion of the total surface of a valve
reaching a pressure higher than a designed pressure, the relief
valve 27 has a pressure pad 27a for opening the valve against the
resistance of the spring 28 to release the pressure.
FIG. 14 shows by-pass line 19 and the accumulator 18 which are
mounted on the surface of the casing 11 of the high damping device
10. A check valve 20a, for preventing an oil flow toward the side
of the hydraulic chamber 14a, is provided between the hydraulic
chamber 14a and the accumulator 18, and a check valve 20b for
preventing an oil flow toward the side of the hydraulic chamber 14b
is provided between a hydraulic chamber 14b and the accumulator.
Moreover, check valves 20a and 20b are attached to orifices 21a and
21b, respectively, passing through each of the check valves (in
parallel with each other as shown in FIG. 10) to linearize the
damping characteristics of the high damping device 10 and to
relieve a pressure build-up within either hydraulic chamber 14a or
14b.
FIGS. 15 through 22 show installation embodiments of the high
damping device 10 within a column-and-beam type frame.
In the embodiment of FIG. 15, the high damping device 10 is
interposed between a column-and-beam frame 31 and an inverted
V-type brace 35, which functions as the earthquake-resisting
element.
The embodiment shown in FIG. 16 employs U-shaped braces 41 which
act as earthquake-resisting elements. The high damping device 10 is
secured between the U-shaped braces 41, which are secured to beams
34 and extend vertically therefrom.
In the embodiment of FIG. 17, the high damping device 10 is
interposed between the upper beam 34 and an earthquake-resisting
wall brace 42.
In the embodiment shown in FIG. 18, the high damping device 10 is
secured between the lower beam 34 and the base B of a structure
mounted on base isolation pads 43. The earthquake-resisting element
is an inverted V-type brace 35, similar to the brace shown in FIG.
15.
In the embodiment of FIG. 19, an earthquake-resisting X-type brace
44 is installed within the column-and-beam frame 31. The high
damping device 10 is horizontally secured at the center of the
brace.
In an embodiment similar to that of FIG. 19, the embodiment shown
in FIG. 20 comprises the high damping device 10 vertically secured
to an X-type brace 45.
In an embodiment similar to that shown in FIG. 17, the embodiment
shown in FIG. 21 discloses the high damping device 10 interposed
between the beam 34 and an earthquake-resisting wall brace 46,
wherein the high damping device 10 is secured to the vertical edge
of the wall brace 46 and over a doorway 47.
In the embodiment shown in FIG. 22, the high damping device 10 is
horizontally interposed at the center of an X-type brace 48 which
extends over three stories of a structure, from floor 49A to floor
49D, with the extremities of the X-type brace secured only to
floors 49A and 49D.
POSSIBILITY OF INDUSTRIAL UTILIZATION
The following advantages will be obtained by applying a high
damping device of the present invention to buildings which are at
risk to the ravages of earthquakes and high winds.
1. Since the number of columns of a column-and-beam structure can
be reduced by approximately 50%, not only is the saving in
structural steel considerable, but the additional unobstructed
floor space between columns considerably increases the floor
planning possibilities.
2. Since the response of the structure to earthquake shock and high
winds is reduced, the safety of the occupants and of the structure
is increased.
3. Since the invention is a passive type damper mechanism, only
fine tuning adjustments to the particular characteristics of the
structure are required when installed.
4. Since complicated active seismic control systems and attached
facilities are not required, installation costs are low in
comparison to the costs of active seismic response control
mechanisms.
5. The effective load applied to the inventive high damping device
may be decreased by reducing the damping coefficient for seismic
vibration to a predetermined safe level.
6. The number of inventive damping devices to be installed on each
floor of a building can be predetermined.
7. Since the designed load limit of the inventive device cannot be
exceeded, the cost of material and labor for related support
structure can be reduced and a compact installation can be
obtained.
It will occur to those skilled in the art, upon reading the
foregoing description of the preferred embodiments of the
invention, taken in conjunction with a study of the drawings, that
certain modifications may be made to the invention without
departing from the intent or scope of the invention. It is
intended, therefore, that the invention be construed and limited
only by the appended claims.
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